clc
clear

% var_name  = 'z';
% LevelStep = 40;
var_name  = 'u';
LevelStep = 4;

plev      = 50000;
it        = 61;
FontSize  = 6;
gravity   = 9.81;

ERA_interim = 'D:\Study\Models\hope\source_data\ERA-interim_high_2019_July.nc';

lon1d = ncread(ERA_interim,'longitude');
lat1d = ncread(ERA_interim,'latitude');
level = ncread(ERA_interim,'level');

ilev = find(plev/100==level);

var = ncread(ERA_interim,var_name,[1,1,ilev,it],[Inf,Inf,1,1]);
if strcmp(var_name,'z')
    var = var / gravity;
end

[lat,lon] = meshgrid(lat1d,lon1d);

figure
% plt = pcolor(lon,lat,var);
[plt,h] = contour(lon,lat,var,'LevelStep',LevelStep,'ShowText','on');
clabel(plt,h,'FontSize',FontSize)
colormap(jet)